A conventional digitizing stylus and tablet system measures the movement of a hand-held stylus with respect to the tablet surface and converts the movement to x and y coordinates. In this fashion, movement of a hand-held stylus across a tablet surface can be used to position images on a computer screen. The x and y coordinates are measured via signals transmitted between the stylus and the tablet surface or between the stylus and an external sensing unit. A third degree of freedom is available in some digitizing systems wherein pressure applied to the stylus tip generates an additional signal corresponding to the z axis direction, perpendicular to the tablet surface.
It is often desirable to detect more than these three degrees of freedom (x, y and z) in order to increase control and editing capabilities in a videographic system. In some advanced stylus and tablet systems, known as 6-D systems, the stylus can detect pitch, roll, and yaw in addition to x, y, and z degrees of freedom. However, a 6-D system requires the addition of expensive electromagnetic sensors in the barrel of the stylus and additional sensing units to monitor the output signals. This additional equipment, while adding functionality, also adds to both the complexity and cost of the total system.
A need thus exists for an economical videographic stylus system having more than three degrees of freedom.